The MONICA Project (Multinational MONItoring of trends and determinants in CArdiovascular disease) was established by the World Health Organization as a long-term observation of coronary deaths, coronary care and risk factors in 38 populations from 21 countries in four continents. The ECTIM Study (Etude Cas-Temoins sur l Infarctus du Myocardium) investigates the large differences in coronary heart disease (CHD) incidence and mortality in certain subgroups of the MONICA observation, i.e., between Northern Ireland and France. Thus, the standardized CHD mortality rates in men (25 to 64 years old) were 348, 105, 102, and 78/100,000 in Belfast, Lille, Strasbourg and Toulouse, respectively. The presence of main risk factors, i.e., total cholesterol, blood pressure and cigarette smoking did not explain those remarkable differences. However, a high risk lipid profile was observed more frequently in the controls from Northern Ireland than in France, consisting of high levels of lipoproteins (Lp) containing apo lipoprotein (apo) A-I, but not Apo-AII (Lp A-I), and high levels of Lp containing Apo B and apo E (LpE:B) and Lp containing apo (a) and apo-B (Lp(a):B). Because the concentration of plasma homocyst(e)ine is frequently elevated in patients with CHD and is considered an independent risk factor for atherosclerosis, we measured levels of plasma homocyst(e)ine in survivors of myocardial infarction and in subjects without history of myocardial infarction (controls) from Belfast, Lille and Strasbourg. Data showed that the relative risk for myocardial infarction was increased in subjects with the highest concentration of plasma homocyst(e)ine. The data suggested that the risk for myocardial infarction was graded across the distribution of homocyst(e)ine levels. These results may have important public health implications in the planning of therapeutic interventions on homocyst(e)ine levels